1. Field of the Invention
This invention relates to novel amide derivatives and dermatologic preparations containing the same. More particularly, it relates to dermatologic preparations capable of essentially improving the barrier functions of the horny layer, namely, maintaining normal barrier functions and restoring damaged barrier functions.
2. Description of the Prior Art
The horny layer is located on the outermost side of the skin to cover the whole body to thereby protect the body from external irritation and invasion of foreign substances and inhibit the evaporation of the moisture contained in the body.
When these barrier functions of the horny layer are weakened by some reasons, the skin frequently suffers from troubles such as inflammation or chapping.
Furthermore, it is known that poverty or deficiency of essential fatty acids (for example, arachidonic acid or linoleic acid), which is caused by prolonged intake of foods free from essential fatty acids, would be accompanied by disorders in the barrier functions of the horny layer.
As the results of analyses on intercellular lipids, it has been found out that the intercellular lipids of the horny layer, in particular, O-acylceramide significantly contributes to the maintenance of the above-mentioned barrier functions of the horny layer.
It is believed, furthermore, that lipids secreted from sebaceous glands form a sebaceous membrane on the surface of the skin so as to partially make up for the barrier functions of the horny layer. Thus dermatologic preparations containing, for example, vaseline have been used in order to form a coating on the surface of the skin so as to make up for the barrier functions of the horny layer.
However known dermatologic preparations cannot essentially improve the barrier functions of the horny layer but merely form a tentative coating on the surface of the skin so as to make up for the barrier functions.